99 lines
3.8 KiB
HTML
99 lines
3.8 KiB
HTML
<h1>Release 4.1 IN DEVELOPMENT</h1>
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<p>The main changes since release 4.0 are:</p>
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<ul>
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<li>Convert::copyUnion now always copies between subfields.</li>
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<li>CreateRequest prevents a possible SEGFAULT.</li>
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<li>New stream operators for Field and PVField are provided.</li>
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</ul>
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<h2>Convert::copyUnion</h2>
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<p>Before this method, depending on types for to and from,
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sometimes did a shallow cppy, i. e. just made to shared_ptr for to
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share the same data as from.
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Now it always copies between the subfield of to and from.</p>
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<h2>CreateRequest change</h2>
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<p>createRequest could cause a SEGFAULT if passed a bad argument.
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This has been changed so the it returns a null pvStructure
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and provies an error.</p>
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<h2>New stream operators</h2>
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<p>New steam operators are available for Field and PVField.
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Before to print a Field (or any extension) or a PVField (or any extension)
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it was necessary to have code like:</p>
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<pre><code> void print(StructureConstPtr struct, PVStructurePtr pv)
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{
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if(struct) {
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cout << *struct << endl;
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} else {
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cout << "nullptr\n"
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}
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if(pv) {
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cout << *.struct << endl;
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} else {
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cout << "nullptr\n"
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}
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}
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</code></pre>
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<p>Now it can be done as follows:</p>
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<pre><code> void print(StructureConstPtr struct, PVStructurePtr pv)
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{
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cout << struct << endl;
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cout << pv << endl;
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}
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</code></pre>
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<h1>Release 4.0</h1>
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<p>The main changes since release 3.0.2 are:</p>
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<ul>
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<li>array semantics now enforce Copy On Write.</li>
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<li>String no longer defined.</li>
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<li>timeStamp and valueAlarm name changes</li>
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<li>toString replaced by stream I/O </li>
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<li>union is new type.</li>
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<li>copy is new.</li>
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<li>monitorPlugin is new.</li>
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</ul>
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<h2>New Semantics for Arrays</h2>
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<p>PVScalarArray, PVStructureArray, and PVUnionArray all enforce COW (Copy On Write) Semantics.
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In order to limit memory usage the storage for raw data is managed via a new shared_vector facility.
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This allows multiple instances of array data to use the shared raw data.
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COW is implemented via shared_vectors of const data, i. e. data that can not be modified.</p>
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<h2>String no longer defined</h2>
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<p>This is replaced by std::string.</p>
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<h2>timeStamp and valueAlarm name changes</h2>
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<p>In timeStamp nanoSeconds is changed to nanoseconds.</p>
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<p>In valueAlarm hystersis is changed to hysteresis</p>
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<h2>toString replaced by stream I/O</h2>
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<p>pvData.h and pvIntrospect no longer defines toString
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Instead they have stream support.
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pvIntrospect uses method dump and pvData uses dumpValue.
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For example:</p>
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<pre><code> PVDoublePtr pvValue;
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String buffer;
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pvValue->toString(&buffer);
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cout << buffer << endl;
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buffer.clear();
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pvValue->getField()->toString(&buffer);
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cout << buffer << evdl;
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</code></pre>
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<p>is replaced by</p>
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<pre><code> PVDoublePtr pvValue;
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cout << *pvValue << endl
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cout << *pvValue->getField() << endl;
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</code></pre>
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<h2>union is a new basic type.</h2>
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<p>There are two new basic types: union_t and unionArray.</p>
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<p>A union is like a structure that has a single subfield.
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There are two flavors:</p>
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<ul>
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<li><b>varient union</b> The field can have any type.</li>
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<li><b>union</b> The field can any of specified set of types.</li>
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</ul>
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<p>The field type can be dynamically changed.</p>
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<h2>copy</h2>
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<p>This consists of createRequest and pvCopy.
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createRequest was moved from pvAccess to here.
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pvCopy is moved from pvDatabaseCPP and now depends
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only on pvData, i. e. it no longer has any knowledge of PVRecord.</p>
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<h2>monitorPlugin</h2>
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<p>This is for is for use by code that implements pvAccess monitors.
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This is prototype and is subject to debate.</p>
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<h1>Release 3.0.2</h1>
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<p>This was the starting point for RELEASE_NOTES</p> |